Sadahiko Takeda

Active control method for passing through critical speeds of rotating shafts by changing stiffnesses of the supports with use of memory metals

This paper describes a method of active vibration control for passing through critical speeds of a rotating shaft by use of support springs made of memory metals. In this method the vibration of the shaft due to whirling is controlled by means of on (heating) and off (cooling) heat control of memory metals for bearing supports. In the analysis the exact solution for whirling problems of a multi-stepped and multi-span shaft carrying a disk which is controlled by this method is derived. Numerical calculations have been carried out for some important problems and experimental tests also have been carried out to verify the present control method and the theoretical results.

Thrust bearing using a magnetic fluid lubricant under magnetic fields

Abstract This paper describes a thrust bearing using a magnetic fluid lubricant under a magnetic field. The critical pressures of the bearing versus the magnitude of the magnetic flux densities have been investigated experimentally. It is shown that the critical pressures of the proposed bearing are larger than those of the normal lubricated bearing under high speeds.

Steady state responses of a relaxation-suspension system with unsymmetrical damping force.

This paper presents theoretical and experimental results for the steady state response of a relaxation-suspension system considering the unsymmetrical damping force under periodic excitation. the unsymmetrical damping force has two different values in period of the stroke velocity. In the analysis, exact solutions are obtained by considering the continuity of the response at the boundary in which the damping force varies. Numerical calculations are carried out for various values of the ratio of the damping coefficient. It is found that the reference line of the vibration in the relaxation-suspension system maintains a constant value within the range of the high frequency ratio, while the reference line in the direct-suspension system varies proportionally to the change of frequency ratio. The experimental values agreed fairly well with the theoretical results.

Dynamic transmission torque of a flexible multiple-disc clutch and brake to intermittent loads

Abstract This paper is concerned with a transmission torque of a flexible multiple-disc clutch subjected to dynamic loads. The analysis has been developed on the problem of the clutch subjected to a dynamic load which varies as a half-rectified sine function with time. In the analysis, the elastodynamic theory of a circular plate has been extended to this problem by application of the Laplace transform method. The dynamic pressures and the reaction forces along the edge between discs have been obtained from the conditions of continuity between discs, and from which the transmission torque of the clutch has been concluded. Numerical results of the transmission torque versus time and the deflections and bending moments in the clutch have been given for some important cases